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Test Code GALE Uridine Diphosphate-Galactose 4' Epimerase, Blood

Useful For

Diagnosis of uridine diphosphate-galactose 4' epimerase deficiency

Testing Algorithm

For more information see Galactosemia Testing Algorithm.

Method Name

Enzyme Reaction followed by Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)

Reporting Name

UDP-galactose 4' epimerase, RBC

Specimen Type

Whole Blood EDTA


Ordering Guidance


This test is appropriate for diagnosis of uridine diphosphate-galactose 4' epimerase (GALE) deficiency, but it will not detect galactokinase (GALK) deficiency, galactose-1-phosphate uridyltransferase (GALT) deficiency, or galactose mutarotase (GALM) deficiency.

-To evaluate for GALK deficiency, order GALK / Galactokinase, Blood.

-To evaluate for GALT deficiency, order GALT / Galactose-1-Phosphate Uridyltransferase, Blood.

-To evaluate for GALM deficiency, order GALP / Galactose, Plasma and molecular analysis of the GALM gene.

 

This assay is not appropriate for monitoring dietary compliance for patients with GALE deficiency. If dietary monitoring is needed, order GAL1P / Galactose-1-Phosphate, Erythrocytes.



Necessary Information


Patient's age is required.

 

Biochemical Genetics Patient Information (T602) is recommended, but not required, to be filled out and sent with the specimen to aid in the interpretation of test results.



Specimen Required


Multiple whole blood tests for galactosemia can be performed on 1 specimen. Prioritize order of testing when submitting specimens. For a list of tests that can be ordered together, see Galactosemia-Related Test List.

 

Container/Tube:

Preferred: Lavender top (EDTA)

Acceptable: Green top (sodium or lithium heparin) or yellow top (ACD)

Specimen Volume: 5 mL


Specimen Minimum Volume

2 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Whole Blood EDTA Refrigerated (preferred) 14 days
  Ambient  6 days

Reference Values

≥3.5 nmol/h/mg of hemoglobin

Interpretation

Results below 3.5 nmol/h/mg of hemoglobin in properly submitted specimens have different causes from carrier status for a disease-causing variant in the GALE gene (typically reduced uridine diphosphate-galactose 4' epimerase [GALE] activity close to the normal activity range) to generalized epimerase deficiency galactosemia due to biallelic disease-causing variants in the GALE gene that markedly reduce GALE activity. Further differentiation requires additional biochemical and molecular genetic analyses as well as correlation with clinical signs and symptoms.

 

Normal results (≥3.5 nmol/hour/mg of hemoglobin) are not consistent with galactosemia due to GALE deficiency.

Clinical Reference

1. Fridovich-Keil J, Bean L, He M, Schroer R. Epimerase deficiency galactosemia. In: Adam MP, Feldman J, Mirzaa GM,, et al. eds. GeneReviews [Internet]. University of Washington, Seattle; 2011. Updated March 11, 2021. Accessed September 12, 2024. Available at www.ncbi.nlm.nih.gov/books/NBK51671/

2. Walter JH, Fridovich-Keil JL. Galactosemia. In: Valle D, Antonarakis S, Ballabio A, Beaudet AL, Mitchell GA, eds. The Online Metabolic and Molecular Bases of Inherited Disease. McGraw-Hill; 2019. Accessed September 12, 2024. Available at https://ommbid.mhmedical.com/content.aspx?bookid=2709&sectionid=%20225081023

3. Timson DJ. Type IV galactosemia. Genet Med. 2019;21(6):1283-1285. doi:10.1038/s41436-018-0359-z

4. Wada Y, Kikuchi A, Arai-Ichinoi N, et al. Biallelic GALM pathogenic variants cause a novel type of galactosemia. Genet Med. 2019;21(6):1286-1294. doi:10.1038/s41436-018-0340-x

Day(s) Performed

Friday

Report Available

6 to 12 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information

82542

LOINC Code Information

Test ID Test Order Name Order LOINC Value
GALE UDP-galactose 4' epimerase, RBC 79469-3

 

Result ID Test Result Name Result LOINC Value
64372 UDP-galactose 4' epimerase, RBC 79469-3
37979 Interpretation (GALE) 59462-2
37978 Reviewed By 18771-6

Forms

1. New York Clients-Informed consent is required. Document on the request form or electronic order that a copy is on file. The following documents are available:

-Informed Consent for Genetic Testing (T576)

-Informed Consent for Genetic Testing-Spanish (T826)

2. Biochemical Genetics Patient Information (T602) is recommended.

3. If not ordering electronically, complete, print, and send a Biochemical Genetics Test Request (T798) with the specimen.